WO2013060775A1 - Method and device at a vehicle differential brake - Google Patents

Method and device at a vehicle differential brake Download PDF

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Publication number
WO2013060775A1
WO2013060775A1 PCT/EP2012/071146 EP2012071146W WO2013060775A1 WO 2013060775 A1 WO2013060775 A1 WO 2013060775A1 EP 2012071146 W EP2012071146 W EP 2012071146W WO 2013060775 A1 WO2013060775 A1 WO 2013060775A1
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WO
WIPO (PCT)
Prior art keywords
clutch
vehicle
hydraulic pressure
differential
preparatory hydraulic
Prior art date
Application number
PCT/EP2012/071146
Other languages
French (fr)
Inventor
Niklas WESTERLUND
Original Assignee
Borgwarner Torqtransfer Systems Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Borgwarner Torqtransfer Systems Ab filed Critical Borgwarner Torqtransfer Systems Ab
Priority to RU2014115865A priority Critical patent/RU2614374C2/en
Priority to CN201280050915.2A priority patent/CN103930294B/en
Priority to US14/350,114 priority patent/US9470300B2/en
Priority to EP12775703.7A priority patent/EP2748026B1/en
Priority to KR1020147009849A priority patent/KR101999763B1/en
Priority to JP2014537612A priority patent/JP6445327B2/en
Publication of WO2013060775A1 publication Critical patent/WO2013060775A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H48/00—Differential gearings
    • F16H48/20—Arrangements for suppressing or influencing the differential action, e.g. locking devices
    • F16H48/22—Arrangements for suppressing or influencing the differential action, e.g. locking devices using friction clutches or brakes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K17/00—Arrangement or mounting of transmissions in vehicles
    • B60K17/04—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing
    • B60K17/16—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of differential gearing
    • B60K17/20—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of differential gearing in which the differential movement is limited
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D48/00—External control of clutches
    • F16D48/06—Control by electric or electronic means, e.g. of fluid pressure
    • F16D48/066—Control of fluid pressure, e.g. using an accumulator
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/10—System to be controlled
    • F16D2500/102—Actuator
    • F16D2500/1021—Electrical type
    • F16D2500/1023—Electric motor
    • F16D2500/1024—Electric motor combined with hydraulic actuation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/10—System to be controlled
    • F16D2500/104—Clutch
    • F16D2500/10406—Clutch position
    • F16D2500/10412—Transmission line of a vehicle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/10—System to be controlled
    • F16D2500/104—Clutch
    • F16D2500/10406—Clutch position
    • F16D2500/10425—Differential clutch
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/30—Signal inputs
    • F16D2500/302—Signal inputs from the actuator
    • F16D2500/3024—Pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/30—Signal inputs
    • F16D2500/31—Signal inputs from the vehicle
    • F16D2500/3101—Detection of a brake actuation by a sensor on the brake
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/30—Signal inputs
    • F16D2500/31—Signal inputs from the vehicle
    • F16D2500/3108—Vehicle speed
    • F16D2500/3109—Vehicle acceleration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/30—Signal inputs
    • F16D2500/314—Signal inputs from the user
    • F16D2500/31406—Signal inputs from the user input from pedals
    • F16D2500/31426—Brake pedal position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/50—Problem to be solved by the control system
    • F16D2500/501—Relating the actuator
    • F16D2500/5014—Filling the actuator cylinder with fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/50—Problem to be solved by the control system
    • F16D2500/52—General
    • F16D2500/525—Improve response of control system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/70—Details about the implementation of the control system
    • F16D2500/704—Output parameters from the control unit; Target parameters to be controlled
    • F16D2500/70402—Actuator parameters
    • F16D2500/70406—Pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/70—Details about the implementation of the control system
    • F16D2500/704—Output parameters from the control unit; Target parameters to be controlled
    • F16D2500/70402—Actuator parameters
    • F16D2500/7041—Position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/70—Details about the implementation of the control system
    • F16D2500/704—Output parameters from the control unit; Target parameters to be controlled
    • F16D2500/70422—Clutch parameters
    • F16D2500/70426—Clutch slip
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D2500/00—External control of clutches by electric or electronic means
    • F16D2500/70—Details about the implementation of the control system
    • F16D2500/706—Strategy of control
    • F16D2500/70663—State analysis; Analysing potential states of the machine and developing control strategies at each state
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H48/00—Differential gearings
    • F16H48/20—Arrangements for suppressing or influencing the differential action, e.g. locking devices
    • F16H2048/204—Control of arrangements for suppressing differential actions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H48/00—Differential gearings
    • F16H48/20—Arrangements for suppressing or influencing the differential action, e.g. locking devices
    • F16H48/30—Arrangements for suppressing or influencing the differential action, e.g. locking devices using externally-actuatable means
    • F16H48/32—Arrangements for suppressing or influencing the differential action, e.g. locking devices using externally-actuatable means using fluid pressure actuators

Definitions

  • the present invention relates to a method in a driveline in a vehicle, preferably a front wheel drive vehicle, for controlling the distribution of drive torque to two drive wheels via a differential being provided with a differential brake with a hydraulically controlled limited slip clutch. It also relates to a device for carrying out this method.
  • the differential brake electronically controlled via the clutch, is only used at certain driving conditions, and it may thus take several minutes or more under normal driving conditions between two consecutive operations thereof. This means that the clutch may return to an "idling" condition (with its clutch discs fully separated from each other) and that the response time, when a controlling torque is needed in the clutch, may be long.
  • the main object of the invention is to remove the drawback with the long response time in certain situations. This is according to the invention attained in that a low preparatory hydraulic pressure is applied to the clutch at the occurrence of any one of certain predetermined driving situations.
  • This preparatory hydraulic pressure is preferably of a magnitude to bring clutch discs of the clutch in contact with each other but not to influence driving dynamics of the vehicle and may be applied in situations, where a controlling action of the clutch may be envisaged shortly.
  • the preparatory hydraulic pressure may for example be applied a certain time after the brake pedal of the vehicle is released, or when the vehicle is accelerating while negotiating a sharp curve, or when the steering wheel of the vehicle, running at high speed, is turned.
  • Fig 1 is a schematic illustration of a driveline layout for a front wheel drive (FWD) road vehicle
  • Fig 2 is an exemplary hydraulic scheme for a control system of a limited clutch in the driveline of Fig 1
  • Fig 3 is a block diagram to illustrate the invention.
  • Fig 1 is a schematic illustration of a driveline layout for a front wheel drive (FWD) road vehicle.
  • the vehicle has two driven front wheels 1 and two undriven rear wheels 2 in a chassis.
  • the front wheels 1 are driven by an engine 3 via a gear box 4 and two half-axles 5, connected by means of a conventional differential 6, capable of transmitting torque to the two half-axles 5, which may rotate with different speeds for example at curve negotiation.
  • the ground grip for one drive wheel 1 may be partially or totally lost, resulting in wheel slip and loss of torque transfer or traction for the other drive wheel.
  • This undesirable effect of the conventional differential may as known be obviated by the provision of a differential brake, which has the effect of partially or totally "short-circuiting" the differential by connecting the two half-axles 5 with each other.
  • a differential brake in the form of a hydraulically controlled, limited slip clutch 7 is illustrated in Fig 1. By engaging this clutch 7 the speed differential and torque distribution between the two half-axles may be controlled.
  • Fig 2 illustrates a hydraulic control system, which is an example of a system that can be used for controlling multiple discs or a disc package 8 of the limited slip clutch 7.
  • This hydraulic control system is previously shown and described in detail in WO 2011/043722, to which reference is made. It may herein suffice to note the presence of a hydraulic pump 10 driven by an electric motor 11. On the same shaft as the pump 10 there is a centrifugal regulator 12 controlling the position of a pressure overflow valve 13. The system also contains a relief valve 14.
  • the motor 11 is constantly running, but its rotational speed is increased for increasing the hydraulic pressure to the cylinder 9 and thus for engaging the multiple discs 8 of the clutch 7.
  • the clutch 7 can be controlled by the system with great accuracy and with reasonably low response time due to the constantly running motor 11.
  • the maximum hydraulic pressure in the system may for example be set at 40 bar.
  • the differential brake in the form of the clutch 7 is only operational under certain circumstances to be dealt with below. Such circumstances may only occur at rather long intervals, such as several minutes or more. This means that the hydraulic control system is "idling" and that the hydraulic pressure therein goes down to nil, so that the multiple discs 8 of the clutch 7 are at maximum distance from each other.
  • the time for pressurizing the hydraulic system and compressing the multiple discs 8 may be in the order of > 250 ms, which may be too much in this use for controlling a differential brake.
  • a solution to the problem with too long response times may according to the invention be to apply a certain low preparatory hydraulic pressure in the cylinder 9, when certain predetermined driving situations occur.
  • driving situations may be detected by existing means in the vehicle, and the processing for applying this pressure may be handled by the ordinary electronic control system for the differential brake.
  • the preparatory hydraulic pressure shall be so low that the driving dynamics of the vehicle are not influenced, but still high enough for applying the discs of the multiple discs 8 against each other or in other words for reaching a "kiss-point" for the disc package.
  • the preparatory pressure may for example be in the order of 1 bar. The use of the preparatory hydraulic pressure may drastically improve the response time after an "idling" interval.
  • the software of the electronic control system for the differential brake may in one version contain three main areas: pre-load, slip-control and yaw-damping.
  • the pre-load area of the software may engage or lock the clutch 7, when the vehicle is to be started from a standstill. This is a preventive measure to avoid loosing the grip for any of the driving wheels, having a poorer grip on the ground than the other.
  • the slip-control will apply a torque on the clutch 7 at the occurrence of a decreased grip for one of the driving wheels during operation.
  • the yaw-damping will apply a torque on the clutch 7, when over-steering of the vehicle occurs, and tends to right or stabilize the vehicle.
  • the preparatory hydraulic pressure may be applied by an electronic response system in the following driving situations requiring quicker response times than may be provided without the preparatory hydraulic pressure.
  • a sharp curve is negotiated during acceleration.
  • the gas pedal position in combination with the high lateral acceleration indicates that the inner drive wheel may loose its grip and start spinning.
  • the preparatory hydraulic pressure is applied for decreasing the response time if needed for the slip-control torque.
  • Fig 3 is a block diagram illustrating the invention.
  • a data bus in a modern vehicle contains detailed information about the vehicle and its behavior during driving. The vehicle state is thus constantly calculated. If a predetermined driving situation requiring a quick response from the clutch 7 occurs, the response system controls the application of the preparatory hydraulic pressure for engaging the disc package 8 to the "kiss-point".
  • the invention has been shown and described in its use for a front wheel drive vehicle, but its basic ideas are equally applicable to a rear wheel drive vehicle.

Abstract

In a driveline in a front wheel drive vehicle the distribution of drive torque to the drive wheels (1) via a differential (6) is controlled by means of a differential brake with a hydraulically controlled limited slip clutch (7). A low preparatory hydraulic pressure is applied to the clutch at the occurrence of any one of certain predetermined driving situations for decreasing the response time for the clutch.

Description

METHOD AND DEVICE AT A VEHICLE DIFFERENTIAL BRAKE Technical Field
The present invention relates to a method in a driveline in a vehicle, preferably a front wheel drive vehicle, for controlling the distribution of drive torque to two drive wheels via a differential being provided with a differential brake with a hydraulically controlled limited slip clutch. It also relates to a device for carrying out this method.
Background of the Invention
The differential brake, electronically controlled via the clutch, is only used at certain driving conditions, and it may thus take several minutes or more under normal driving conditions between two consecutive operations thereof. This means that the clutch may return to an "idling" condition (with its clutch discs fully separated from each other) and that the response time, when a controlling torque is needed in the clutch, may be long.
The Invention
The main object of the invention is to remove the drawback with the long response time in certain situations. This is according to the invention attained in that a low preparatory hydraulic pressure is applied to the clutch at the occurrence of any one of certain predetermined driving situations.
This preparatory hydraulic pressure is preferably of a magnitude to bring clutch discs of the clutch in contact with each other but not to influence driving dynamics of the vehicle and may be applied in situations, where a controlling action of the clutch may be envisaged shortly.
The preparatory hydraulic pressure may for example be applied a certain time after the brake pedal of the vehicle is released, or when the vehicle is accelerating while negotiating a sharp curve, or when the steering wheel of the vehicle, running at high speed, is turned.
Brief Description of the Drawings
The invention will be described in further detail below under reference to the accompanying drawings, in which
Fig 1 is a schematic illustration of a driveline layout for a front wheel drive (FWD) road vehicle,
Fig 2 is an exemplary hydraulic scheme for a control system of a limited clutch in the driveline of Fig 1, and Fig 3 is a block diagram to illustrate the invention.
Detailed Description of Embodiments
Fig 1 is a schematic illustration of a driveline layout for a front wheel drive (FWD) road vehicle. The vehicle has two driven front wheels 1 and two undriven rear wheels 2 in a chassis. As is well known to any person skilled in the art, the front wheels 1 are driven by an engine 3 via a gear box 4 and two half-axles 5, connected by means of a conventional differential 6, capable of transmitting torque to the two half-axles 5, which may rotate with different speeds for example at curve negotiation.
At certain situations, the ground grip for one drive wheel 1 may be partially or totally lost, resulting in wheel slip and loss of torque transfer or traction for the other drive wheel. This undesirable effect of the conventional differential may as known be obviated by the provision of a differential brake, which has the effect of partially or totally "short-circuiting" the differential by connecting the two half-axles 5 with each other. A differential brake in the form of a hydraulically controlled, limited slip clutch 7 is illustrated in Fig 1. By engaging this clutch 7 the speed differential and torque distribution between the two half-axles may be controlled.
Fig 2 illustrates a hydraulic control system, which is an example of a system that can be used for controlling multiple discs or a disc package 8 of the limited slip clutch 7. When the discs 8 are brought into engagement with each other by a hydraulic cylinder 9, the clutch 7 is engaged. This hydraulic control system is previously shown and described in detail in WO 2011/043722, to which reference is made. It may herein suffice to note the presence of a hydraulic pump 10 driven by an electric motor 11. On the same shaft as the pump 10 there is a centrifugal regulator 12 controlling the position of a pressure overflow valve 13. The system also contains a relief valve 14.
The motor 11 is constantly running, but its rotational speed is increased for increasing the hydraulic pressure to the cylinder 9 and thus for engaging the multiple discs 8 of the clutch 7. The clutch 7 can be controlled by the system with great accuracy and with reasonably low response time due to the constantly running motor 11. The maximum hydraulic pressure in the system may for example be set at 40 bar.
As already stated, the differential brake in the form of the clutch 7 is only operational under certain circumstances to be dealt with below. Such circumstances may only occur at rather long intervals, such as several minutes or more. This means that the hydraulic control system is "idling" and that the hydraulic pressure therein goes down to nil, so that the multiple discs 8 of the clutch 7 are at maximum distance from each other. When there is a need for engaging the clutch 7, the time for pressurizing the hydraulic system and compressing the multiple discs 8 may be in the order of > 250 ms, which may be too much in this use for controlling a differential brake.
A solution to the problem with too long response times may according to the invention be to apply a certain low preparatory hydraulic pressure in the cylinder 9, when certain predetermined driving situations occur. Such driving situations may be detected by existing means in the vehicle, and the processing for applying this pressure may be handled by the ordinary electronic control system for the differential brake.
The preparatory hydraulic pressure shall be so low that the driving dynamics of the vehicle are not influenced, but still high enough for applying the discs of the multiple discs 8 against each other or in other words for reaching a "kiss-point" for the disc package. At a maximum hydraulic pressure in the system of 40 bar, the preparatory pressure may for example be in the order of 1 bar. The use of the preparatory hydraulic pressure may drastically improve the response time after an "idling" interval.
The software of the electronic control system for the differential brake may in one version contain three main areas: pre-load, slip-control and yaw-damping.
The pre-load area of the software may engage or lock the clutch 7, when the vehicle is to be started from a standstill. This is a preventive measure to avoid loosing the grip for any of the driving wheels, having a poorer grip on the ground than the other.
The slip-control will apply a torque on the clutch 7 at the occurrence of a decreased grip for one of the driving wheels during operation.
The yaw-damping will apply a torque on the clutch 7, when over-steering of the vehicle occurs, and tends to right or stabilize the vehicle.
In this environment and only to be seen as examples of uses, the preparatory hydraulic pressure may be applied by an electronic response system in the following driving situations requiring quicker response times than may be provided without the preparatory hydraulic pressure.
- The vehicle holds at red light, and the driver has the foot brake applied. When the brake pedal is released, the preparatory hydraulic pressure is applied for say 2 seconds for improving the response time for the pre-load to possibly come. If the preload is not used within this time period, it has to be assumed that the preparatory hydraulic pressure is not needed, because the driver did not plan a quick start.
- A sharp curve is negotiated during acceleration. The gas pedal position in combination with the high lateral acceleration indicates that the inner drive wheel may loose its grip and start spinning. The preparatory hydraulic pressure is applied for decreasing the response time if needed for the slip-control torque.
- The steering wheel is turned somewhat, when the vehicle is running at high speed. This indicates that a yaw-damping may be needed, and the preparatory hydraulic pressure is applied.
It shall be noted that other driving situations where the quick response of the clutch 7 may be required are possible. Also, it is important to note that the invention is not limited to its use with the shown and described clutch and its control system.
Fig 3 is a block diagram illustrating the invention. A data bus in a modern vehicle contains detailed information about the vehicle and its behavior during driving. The vehicle state is thus constantly calculated. If a predetermined driving situation requiring a quick response from the clutch 7 occurs, the response system controls the application of the preparatory hydraulic pressure for engaging the disc package 8 to the "kiss-point".
The invention has been shown and described in its use for a front wheel drive vehicle, but its basic ideas are equally applicable to a rear wheel drive vehicle.
Modifications are possible within the scope of the appended claims.

Claims

1. A method in a driveline in a vehicle, preferably a front wheel drive vehicle, for controlling the distribution of drive torque to two drive wheels (1) via a differential (6) being provided with a differential brake with a hydraulically controlled limited slip clutch (7), characterized in that a low preparatory hydraulic pressure is applied to the clutch (7) at the occurrence of any one of certain predetermined driving situations.
2. A method according to claim 1, wherein the preparatory hydraulic pressure is of a magnitude to bring clutch discs (8) of the clutch (7) in contact with each other but not to influence driving dynamics of the vehicle.
3. A method according to claim 1, wherein the preparatory hydraulic pressure is applied in situations, where a controlling action of the clutch (7) may be envisaged shortly.
4. A method according to claim 3, wherein the preparatory hydraulic pressure is applied a certain time after the brake pedal of the vehicle is released.
5. A method according to claim 3, wherein the preparatory hydraulic pressure is applied, when the vehicle is accelerating while negotiating a sharp curve.
6. A method according to claim 3, wherein the preparatory hydraulic pressure is applied, when the steering wheel of the vehicle, running at high speed, is turned.
7. A driveline in a vehicle, preferably a front wheel drive vehicle, comprising a differential (6) for distributing a drive torque to two drive wheels (1) and a differential brake with a hydraulically controlled limited slip clutch (7), characterized by a response system for controlling the supply of a preparatory hydraulic pressure to the clutch (7) at the occurrence of any one of certain predetermined driving situations.
PCT/EP2012/071146 2011-10-25 2012-10-25 Method and device at a vehicle differential brake WO2013060775A1 (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
RU2014115865A RU2614374C2 (en) 2011-10-25 2012-10-25 Method and device for vehicle differential brake
CN201280050915.2A CN103930294B (en) 2011-10-25 2012-10-25 The method and apparatus of vehicle differential braking
US14/350,114 US9470300B2 (en) 2011-10-25 2012-10-25 Method and device at a vehicle differential brake
EP12775703.7A EP2748026B1 (en) 2011-10-25 2012-10-25 Method and device at a vehicle differential brake
KR1020147009849A KR101999763B1 (en) 2011-10-25 2012-10-25 Method and device at a vehicle differential brake
JP2014537612A JP6445327B2 (en) 2011-10-25 2012-10-25 Vehicle differential braking method and apparatus

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JP (1) JP6445327B2 (en)
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US20080190729A1 (en) * 2005-07-01 2008-08-14 Luk Lamellen Und Kupplungsbau Beteiligungs Kg Method and apparatus for controlling a motor vehicle clutch
EP2116410A1 (en) * 2007-01-30 2009-11-11 Toyota Jidosha Kabushiki Kaisha Controller for limited slip differential devices for vehicles
WO2011043722A1 (en) 2009-10-06 2011-04-14 Haldex Traction Ab A hydraulic pump assembly

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CN103930294A (en) 2014-07-16
US9470300B2 (en) 2016-10-18
KR101999763B1 (en) 2019-07-12
RU2014115865A (en) 2015-12-10
RU2614374C2 (en) 2017-03-24
JP2014534116A (en) 2014-12-18
KR20140079405A (en) 2014-06-26
CN103930294B (en) 2018-01-19
EP2748026B1 (en) 2016-12-14
US20140256492A1 (en) 2014-09-11
EP2748026A1 (en) 2014-07-02
JP6445327B2 (en) 2018-12-26

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